void main() {
  Map category = {
    'id': 1,
    'name': '手机',
    0: '苹果',
    [0, 1]: '华为',
  };

  print(category['name']); //手机
  print(category[0]); //苹果
  print(category['id']); //1

  category['price'] = 999.88;
  print(category);

  category.remove('name');
  print(category);

  category.forEach((key, value) {
    print('key: $key, value: $value');
  });
}
